In the past, digestive enzyme inhibitors such as Basen (Takeda Pharmaceutical), containing voglibose, and Glucobay (Bayer), containing acarbose, have actually been used clinically as effective therapeutic drugs for hyperglycemia. However, since both compounds inhibit α-glucosidase, they have the disadvantages of causing adverse side effects such as abdominal distention, flatulence, increased abdominal wind, soft stools, diarrhea and abdominal pain. Moreover, they have also been reported to cause liver function disorders.
On the other hand, effects causing inhibition of the absorption of nutrients are known to be obtainable by inhibiting not only α-glucosidase, but α-amylase as well, and compounds are known that lower blood glucose levels without causing the aforementioned adverse side effects unique to α-glucosidase inhibitors. However, the α-amylase activity of these compounds is weak, and there are no compounds known that have adequate α-amylase inhibitory activity.
Compounds having a partial structure (sugar derivative) that is in common with the oligosaccharide derivative of the present invention that demonstrate α-amylase inhibitory activity have been disclosed (see, for example, International Publication WO 00/50434 and International Publication WO 01/94367). However, these compounds differ from the compound of the present invention in that they are required to have a deoxynojirimycin backbone or a hexahydro-3,5,6-trihydroxy-1H-azepine backbone.